The typical modern nursing home or hospital bed is provided with means for raising and lowering the mattress of the bed without changing the tilt of the mattress, for raising and lowering the head half of the mattress with a bend at its midpoint, and for raising and lowering the intermediate portion of the mattress underlying the knees of the patient. It is often desired or necessary for proper medical treatment procedures to elevate the patient's head or feet while maintaining the flat or planar configuration of the mattress itself, positions sometimes referred to as reverse Trendelenburg and as Trendelenburg, respectively. Various approaches to elevating the head or foot of the bed are known in the prior art, but each of the prior art approaches suffers from certain disadvantages.
In on such approach, one end of either the mattress support structure or the entire bed is raised by manual lifting, and propped at the desired position with blocks, bricks or the like placed between the mattress support structure and the bed frame or between the bed and the floor. While the simple expedient of propping up the mattress or the entire bed does allow elevation of one end of the mattress or bed, this approach has several disadvantages. The blocks used to prop the mattress or bed may be easily dislodged, allowing the elevated structure to fall to its rest position, with significant risk of injury to the patient. Further, especially when the entire bed is elevated at one end, it is difficult or impossible to move the bed without lowering the mattress to a horizontal position, and it is difficult to adjust the angle of elevation.
In another approach, the bed is provided with legs supporting it above the floor, and the legs are adapted to be adjustable in length, usually in pairs, as illustrated by U.S. Pat. No. 3,073,635 to Schaefer. In the Schaefer patent, the legs telescope into the head board and foot board of the bed, with the head pair of legs and the foot pair of legs selectively operable for tilting the plane of the entire bed frame. In another similar approach, illustrated by U.S. Pat. No. 3,802,002 to Jonas, the legs are of fixed length and are pivotally interconnected to a generally horizontal bed frame member. In the Jonas example, the elevation of either end of the bed may be adjusted by changing the angle between a respective pair of legs and the bed frame member. While effective for the particular purpose of elevating the bed, this approach may require adjustments to be made from various locations around the bed, depending upon the adjustment desired, and do not allow the mattress support or frame to be adjusted without changing the position of the entire bed frame.
A third approach known in the prior art, illustrated by U.S. Pat. No. 4,174,547 to Wetzler, utilizes a series of lever arms to rapidly raise and lower the head and/or the foot of the mattress supporting structure independent of the remainder of the bed structure, primarily in emergency situations. A pair of lever arms is associated with the head of the mattress structure, a second pair of lever arms is associated with the foot of the mattress structure, with each head lever arm connected to a foot lever arm by an elongate connecting rod. The lever arms are selectively rotated by means of a transverse concentric tube and rod assembly driven by a motor, and the head arms may be disconnected from the foot arms through a clutch arrangement. While reasonably effective for its intended purpose, the approach illustrated by the Wetzler patent requires a mechanically complex, and thus relatively costly, apparatus for operation.
There remains a need in the industry for a mechanically reliable, economical apparatus for the selective raising and lowering of the head and foot of a hospital or nursing home bed which is readily operable from a single point on the bed, and which does not interfere with movement of the bed or care of the patient reclining upon the bed.